Effect of triheptanoin on muscle metabolism during submaximal exercise in horses.

The study investigates the impact of triheptanoin, a 7-carbon fat, and corn oil on certain metabolic functions in exercising horses, demonstrating that triheptanoin triggers higher insulin secretion without enhancing muscle glycogen repletion compared to corn oil.

Study Design and Methods

• Eight thoroughbred gelding horses were chosen for this research.
• The horses were given isocaloric diets that contained 650 mL of either triheptanoin or corn oil each day for an 18 to 25-day period. The study employed a crossover design, with a 26-day washout interval.
• On the 17th or 24th day of each dietary period, the horses were further administered 217 mL of the respective oil through a nasogastric tube.
• Subsequent to oil administration, horses underwent a 90-minute submaximal exercise test (SET) after 120 minutes.
• Blood and muscle samples were collected at various stages: before administration of the oil, right before the SET (blood only), during the SET (blood only), immediately after the SET, and 24 hours post-SET.

Results and Findings

• After administration of oils, triheptanoin led to a surge in plasma insulin and in C7:0, C5:0, and C3:0-acylcarnitine concentrations. However, corn oil administration increased plasma non-esterified fatty acids (NEFA) concentrations.
• During SETs, the plasma concentrations of C7:0, C5:0, and C3:0-acylcarnitine were higher when horses were given triheptanoin instead of corn oil.
• Both oils similarly increased plasma glucose, NEFA, and C2:0, C18:1, and C18:2-acylcarnitine concentrations during SETs.
• The respiratory quotient and muscle lactate, citrate, malate, glycogen, and ATP concentrations changed similarly from before to after SETs for both oils.
• After 24 hours from the end of SETs, glucose-6-phosphate and citrate concentrations in muscles dropped, while glycogen levels were similar to the pre-SET values.

Conclusions

• The study concluded that neither oils caused fatigue associated with a decrease in citric acid cycle intermediates.
• Triheptanoin resulted in significantly higher insulin secretion but did not seem to enhance muscle glycogen repletion when compared to corn oil.